Hammer attachment for electric drills



March 24, .1931.

E. B. GRUjTZBACH HAMMER ATTACHMENT FOR ELECTRIC -DRILLS Filed July 18, 1928 Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE ERICH BOTHO GBTZBAOE, OF MIAMI, FLORIDA HAMMER ATTACHMENT FOR ELECTRIC DRILLS Application led J'uly 18, 1928. Serial lo. 293,728.

. i chine is to be used as a drill.

In carrying out these objects, the invention is susceptible of a wide range of modification without departing from the spirit or sacricing any of the advantages of the claimed invention; there being shown in the drawings for illustrative purposes a preferred and practical form, in which:

Figure 1 represents a side elevation of a portion of an electric drill with this improved attachment shown applied and in vertical longitudinal section, parts being in elevation;

Fig. 2 is a horizontal section taken onI the line 2 2 of Fig. 1;

Fig. 3 is ya similar view taken on the line 3-3 of Fig. 1 and,

Fig. 4 is another horizontal sectiontaken on the line 4--4 of Fig. 1.

' In the embodiment illustrated an electric d'rill 1 is shown of ordinary construction having the usual tapered spindle 2 designed to be rotated in the ordinary manner. A double-barrelled or double-cylindrical casing 20 as shown in cross section in Figs. 3 and 4 is designed torbe mounted on the spindle 2 and surrounds it and is designed to be attached to the drill by any suitable means. Mounted to reciprocate in one barrel or chamber of the casing 20 is a hammer 10 having a socket 11 in its upper end to form a seat for one end of a coiled spring 12 which bears at its other end against the top portion of the chamber of the casing 20 in which the hammer is located. The spring 12 exerts its A tension normally to force the hammer outward in a manner hereinafter more fully described.

The lower end of the hammer 10 merges into a reduced extension 13 having a shoul- 'der 14 at its junction with the hammer and 55 a coiled spring '15 encircles this extension 13 at its inner end bearin at one end against a sleeve 16 which encirc es the extension and at its other against the shoulder 14 of the hammer. This spring tends to force the ham-y mer inwardly against the tension of spring 12. The sleeve 16 is provided at its outer end with Aan annular flange 17 which is clamped Y between a cap 18 and the other end of the casing 20, said cap being threaded on said casing, as is shown clearly in Fig. 1. The casing 2O has diametrically opposite apertures 21 which register with similar apertures 21a in the sleeve 16. These apertures register with the space 19 formed between 70 the hammer extension 13 and the to'ol 19a and is )designed to form an air relief as the hammer descends. A similar relief is shown at 12a.

The casing chamber in which the hammer '15 10 is mounted is provided with diametricadl opposite slots 23 and 24 lthe latter affordmg communication with the other chamber or barrel pf the casing 20 in which the'cam shaft 26`is located. n

.j A pin 25 extends transversely through the yhammer 10 and projects at opposite ends beyond'the opposite faces of the hammer, said ends being mounted in the slots 23 and 24 to form cooperating guiding elements for the hammer to prevent its rotary movement and guide it in its reciprocatory movement. The inner end of the pin 25 is longer than the outer end and designed to overlie a cam 30 carried by the cam shaft 26 and to travel on the cam face thereof so that the rotation of the cam shaft will cause the hammer 10 to be moved inwardly against the tension of spring '12 and when the pin drops ofi' the end of the cam thespring 12 will operate to project the hammer 10 forcibly beyond the sleeve 16 adapting it to strike a drivingI blow on the tool 19a. The continued rotation of the camshaft operates to again engage" the pin 25 and raise the hammer, or move it inwardly against the tension of spring 12 ready for the next blow.

vA tapered attaching socket 27 is carried by the shank 31 of the shaft 33 and is designed to fit snugly on the tapered spindle 2 when the attachment is applied so that the rotation of the spindle will operate to rotate the shaft. This shaft 33 has an annular collar 34 designed to bear against a horizontal partition 35 in the casing and in which partition the shaft 33 is journalled to rotate. A bearing 36 is located in the lower end of the casing chamber in-which the shaft 33 is mounted and the end of the shaft extension 26 is jour- `nalled in this bearing, the cam 30 being located j ust above as is shown clearly in Fig: 1. The two casing barrels or chambers as shown numbered 20a and 20?). It will be seen that when the attachment is applied to the drill 1 as shown in Fig. 1 the rotation of the spindle 2 will operate to drive the cam shaft 33 continuously rotating the cam 30 'and causing it to raise or retract the hammer 10 .against the spring 12 and then to release the hammer by permitting the pin 25 to drop ofi the end of thecam as shown in Fig. 3 which causes thehammer to be forcibly projected by the spring 12 and exert a striking blow on the rivet or other objects to be driven. The

ing oppositely disposed slots, one of which communicates with the other barrel, a pin extending thrugh said hammer and through said slot, one end of said pin entering the other barrel,A a shaft mounted to rotate in the other barrel, a cam .carried by said shaft and located in the path`oi-` said pin whereby the rotation of the cam shaft wlll cause the hammer to be moved inwardly against the tension of the spring and when the pin is disengaged from the cam said spring will operate to project the hammer forcibly beyond said sleeve to impart a driving blow to a tool to be actuated.

ERICH BOTHO GRUTZBACH.

continued rotation of the cam shaft causes the cam 30 to pass-again under the pin 25 and retractit ready for the next blow so that the hammer will be alternately retracted and projected to operate as a hammer in the ordinary manner. It will also be obvious that the rotary motion ofthe cam shaft will be converted into reciprocatory motion in the hammer incident to the connection of the pin 25 and the cam 30. F Without further description it is thought that the features and advantages of the invention will be readily apparent to those skilled in the art, and it will, of course, be understood that changes in the form, propor- ,tion and' minor details of construction may said hammer having a socket in its upper end `to form a spring seat, a coiled spring arranged in said barrel above said hammer with 4one end engaged with said seat and the other engaging the end wall of the barrel, a reduced extension carried by the lower end of said hammer, a sleeve in said barrel encircling said reduced extension and spaced from the enlarged portion of the hammer, a coiled spring mounted between the upper end of said sleeve andthe lower end of the hammer propy 

